At present, the valve assemblies used for beer kegs can be categorized in two major types.
A first type, the so called A(Iumasc) type, is described in for example WO 0020326 and comprises a cylindrical housing and a cylindrical, cup-shaped base fitted in the open bottom of the housing.
The top of the housing has an inwardly directed annular rim defining an outer peripheral valve seat of the valve port, while in the cylindrical side wall of the housing a series of ports is provided.
The cup-shaped base is provided with a central spigot extending both upward and downward from the base. A valve stem is fitted in the upper part of the spigot. This valve stem is a tubular member provided with a cap at one end and with a series of ports in the tubular side wall adjacent to that cap. The valve stem partially extends out of the spigot such that said series of ports is free.
The cap of the valve stem has an outwardly directed annular rim defining an inner peripheral valve seat coplanar with the outer peripheral valve seat.
A poppet-ring valve member made of a resilient material is provided coaxially around the valve stem and is actuated against the valve seats by means of a spring provided in the valve housing.
The poppet-ring hereby allows sealing the valve port in a closed position. To open the valve port, a dispenser tube is used to press the poppet-ring against the spring past the series of ports in the valve stem. In this open position, the dispenser tube, the valve member and the spigot segregate an internal and external fluid channel.
A second type of valve assemblies is generally named the S(ankey) type and is described in for example GB 1549733. S-type valve assemblies comprise a cylindrical housing and a cup-shaped base movably fitted therein.
The top of the housing has an inwardly directed rim defining an outer peripheral seat of the valve port, while the base of the housing has an inwardly directed flange defining a hole wherein the cup-shaped base is slidebly mounted in a sealing manner.
The cup-shaped base consists of a tubular member with at least one alteration in diameter created by a shoulder portion in the side walls thereof. At its top, the cup-shaped bas has an outwardly extending flange provided with a sealing. The cup-shaped base is actuated by a spring fitted between the base of the housing and the flange at the top of the cup-shaped base, thereby pushing the sealing against the outer peripheral valve seat, closing the outer fluid channel.
In the cup-shaped base is provided a valve plug usually consisting of an integral disc-shaped body with a peripheral transversal flange. The outer peripheral edge of the valve plug defines the inner peripheral valve seat.
A second spring is applied between the valve plug and the shoulder portion in the cup-shaped base, thereby pressing the valve plug against the inner valve seat and closing the inner fluid channel of the valve.
A drawback of the A-type valve assemblies is that the overall design with spigot and cup-shaped base necessitates a substantial amount of material, thereby rendering this type of valve assemblies heavy and expensive.
Another drawback of the A-type valve assemblies is that the sealing is slideble in view of the spigot, while contact between both parts is essential for the segregation between both fluid channels.
An drawback of the known S-type valves is the use of two springs, which render this type of valve quite expensive, both in material cost and in assembly cost. Moreover the fact that the cup-shaped base is movable with respect to the valve housing renders the assembly of the valve rather complex.
EP 0225035 discloses an alternative design allowing replacement of the springs by elastomeric materials. However, the proposed design is rather complex and the cup-shaped base still is slidebly mounted in the valve housing such that assembly of the valve remains complex and expensive.
The object underlying the present invention is to solve the above drawbacks and to present a valve assembly that is more easy to manufacture and reliable in use.